Artificial nails are widely used by women who desire to have long, attractive fingernails which do not break or chip as readily as natural nails. Artificial nails are generally formed directly on the natural nail surface by coating on the nail a layer of a viscous liquid monomer composition comprised of one or more addition polymerizable, ethylenically unsaturated monomers, shaping the material to the desired configuration, then allowing the material to polymerize on the nail surface to yield a hard coating. The resulting artificial nail is then shaped and polished to look like a natural nail. Often the monomer composition comprises one or more esters of acrylic or methacrylic acid and an aliphatic alcohol or ether alcohol, e.g. ethyl acrylate or tetraethylene glycol di-methacrylate.
The preparation and application of artificial nails requires a certain level of skill. In addition, the monomer composition must exhibit certain properties which enable easy application and polymerization of the composition on the nails, while at the same time providing a polymerized nail structure which is strong, yet flexible. Important properties of the monomer composition are gel time, set time, and flexibility. In other words, the monomer composition must reach a certain viscosity in a certain period of time after polymerization is initiated. Otherwise precious minutes are wasted waiting for polymerization to occur, or if the applied monomer composition is not viscous enough when applied to the nail, it will drip off the nail surface and will be difficult to shape. Once the monomer composition is applied to the nails it must set, or polymerize, in a period of time which is adequate to permit a skilled nail technician to apply and shape the composition, but not so long as to have the client waiting for excess periods of time. The monomer composition must be flexible enough so that the nail technician can shape it into the desired configuration prior to setting. The hardened nail structure must be flexible and strong. Flexibility means that the nail can withstand certain amounts of stress without breaking. Too little flexibility causes brittleness and easy breakage. On the other hand, too much flexibility causes reduced strength. Thus, it is important to have a balance between flexibility and strength.
Further, the polymerized artificial nail structure must exhibit adequate adhesion to the nail surface, otherwise it will become dislodged too easily. Generally, artificial nails do not adhere well to nail surfaces. Thus, it is necessary to first coat the nail surface with a primer composition, which is most often acrylic or methacrylic acid alone or in a solvent composition. The primer promotes adhesion of the subsequently applied artificial nail to the nail surface. Obviously, it would be desirable to eliminate use of the primer composition, without lowering adhesion of the artificial nail structure to the nail surface.
Another consistent problem with artificial nails is known as “curling”, or more technically described as “delamination”. This results when the natural nail surface curves away from the artificial nail as the natural nail grows. This delamination provides crevices between the two surfaces, which tend to collect dirt and bacteria. Delamination is a major cause of infection for those who wear artificial nails. Also, delamination causes discomfort and poor hygiene.
In addition, another problem for manufacturers of artificial nail compositions is polymerization of the monomer composition in the container in which it is sold. This is referred to as “premature gelation” or “premature polymerization”. Obviously, product which is polymerized at the time it is received by the nail salon is not suitable for use and is returned to the manufacturer. In some cases, product may be received in the salon which is close to premature polymerization. The salon owner, not realizing this, uses the product to prepare artificial nails. The resulting artificial nails are often deficient in adhesion and strength.
There is a need to improve the gel time, set time, flexibility, strength, adhesion, and other characteristics of artificial nails, as well as to reduce premature gelation and delamination or curling.
It is an object of the invention to provide an artificial nail monomer composition which exhibits improved gel time, set time, and flexibility.
It is an object of the invention to provide a polymerized artificial nail structure which exhibits improved strength, flexibility, and adhesion to the nail.
It is an object of the invention to provide a method for improving adhesion of an artificial nail structure to the nail surface, without the necessity of treating the nail surface with a primer composition.
It is an object of the invention to provide an artificial nail composition which exhibits a reduced tendency toward premature gelation.
It is an object of the invention to provide a method for reducing delamination of the artificial and natural nail surface, or the curling of the natural nail away from the artificial nail structure.